SiC (silicon carbide) is such that since the material has a smaller energy loss at the time of electric current application than silicon, the calorific value is small, and since the heat resistance is high, the material is capable of handling larger electric power. Thus, investigations are being actively conducted on the use of SiC power semiconductors as next-generation power semiconductors that would replace silicon power semiconductor, which is extensively used. While the heat resistance limit temperature of silicon power semiconductor devices is about 150° C., an investigation is being conducted on raising the heat resistance limit temperature of SiC power semiconductor devices to 200° C. to 300° C.
As a class of encapsulating material/insulating material for silicon power semiconductor devices, organopolysiloxane resins (also referred to as silicone resins) have been used (see, for example, Patent Literatures 1 to 5). Organopolysiloxane resins are excellent in heat resistance, electrical insulation properties, weather resistance and the like; however, those conventionally known organopolysiloxane resins cannot be said to have sufficient heat resistance or electrical insulation properties at high temperatures, and the resins have a problem that the electrical insulation properties deteriorate when the resins are put to use for a long time period at a temperature exceeding 200° C. The organopolysiloxane resins have been unsatisfactory as a class of encapsulating material/insulating material for silicon power semiconductor. Particularly, the encapsulating materials/insulating materials for SiC power semiconductors that are used in railway vehicles, hybrid cars, electric cars, electromagnetic cookers and the like, are required to exhibit high electrical insulation properties and sufficient sealability, when used at high temperatures as well as when used repeatedly over a range from a low temperature to a high temperature. However, such an encapsulating material/insulating material has not yet been obtained to date.